You will need 9 X 12 inch clasp envelopes, plastic page protectors and some clear scotch tape. You can find the envelopes at any dollar store. I prefer to use a more expensive page protector because they do not tear as easily as the cheaper version.
Cut the edges off of the page protector so that you have two pieces. (Use the other one for another envelope.)
Tape the sides and bottom of your page protector to the front of your envelope.
Cut the edges from around your paper pattern envelope and then cut it in two. You might have to trim them a little more to get them to fit. Slide the front and back pieces into the front of your envelope. I then tape them to keep them in place. Tape the top part of the page protector.
These fit perfectly in the file drawer of my sewing desk. The envelope is large enough to add fabric samples as well as the pattern pieces.